Recently, a smelting reduction process, which can replace the blast furnace method, has been researched. In the smelting reduction process, raw coal is directly used as a fuel and a reducing agent and iron ore is directly used as an iron source, and thereby iron ore is reduced in a reduction reactor and molten iron is manufactured in a melter-gasifier.
Oxygen is injected into the melter-gasifier and then burns a coal-packed bed therein. The oxygen is converted into a reducing gas and is discharged from the melter-gasifier. The reducing gas discharged from the melter-gasifier is transferred to a reduction reactor. Iron ore is reduced by the reducing gas in the reduction reactor. The reducing gas is discharged from the reduction reactor as an offgas after reducing the iron ore.
Dust contained in the offgas is collected by spraying water, and the offgas is partly reformed and is then used as a reducing gas again. Since the temperature of the offgas is high, the offgas has much sensible heat that is lost during circulation thereof.